A motor vehicle air extraction system provides a number of functions, allowing proper air flow inside a passenger cabin of a motor vehicle, controlling window fogging and even reducing door closing effort. Such an air extraction system incorporates an inlet such as a trim panel inlet, an air extractor and an air duct connecting the trim panel inlet to the air extractor.
In order to accommodate a desired airflow inside the passenger cabin, that air duct is ideally designed to have a large diameter and no expansion chamber. In order to control noise, vibration and harshness (NVH), that air duct is ideally designed to have a small diameter and an expansion chamber. This document relates to a new and improved acoustic air duct and a new and improved air extraction system uniquely designed and adapted to meet these seemingly conflicting requirements. A related method of reducing noise transmitted through an air duct is also provided.